Why do I get a side stitch when running?
A side stitch most likely comes from irritation of the peritoneum, the thin lining of the belly, rubbed by a full stomach and the jolts of the torso. About 70% of runners get one each year (Morton and Callister, 2015). The pain fades quickly once you slow down.
Simplified diagram, not to scale. Dotted curves are estimates based on published surveys; the percentages in the notes are measured.
Why do I get a side stitch when running?
The chest and belly seen from the front, greatly simplified. Choose a situation, then tap a label on the drawing to learn what it is.
Sources: peritoneum lead, moves that bring relief and meals (Morton and Callister, Sports Med, 2015); sports and shoulder (Morton and Callister, Med Sci Sports Exerc, 2000); Sydney race (Morton et al., J Sci Med Sport, 2005); diaphragm (Morton and Callister, 2006); muscles (Morton and Callister, 2008); rounded back (Morton and Callister, 2010); moves tested (Plunkett and Hopkins, 1999); drinks (Morton et al., 2004). Drawing not to scale.
Keyboard: 1 to 3 situations, Space pause, L slow motion, R restart, ← → previous or next step.
Frequently asked questions about side stitches
How do you get rid of a side stitch?
The most effective move is still to stop or slow down; you can also breathe deeply and press on the sore spot while bending forward (Morton and Callister, 2015). Among athletes surveyed, 40% breathe deeply, 31% press on the pain, 22% stretch and 18% bend forward (Morton and Callister, 2015). In 7 runners, breathing out through pursed lips, bending forward while tightening the abs or tightening a belt eased the pain within seconds (Plunkett and Hopkins, 1999).
Why do I get a side stitch when running?
The strongest explanation is irritation of the peritoneum, the thin lining of the belly wall, rubbed by a full stomach and the jolts of the torso (Morton and Callister, 2015). The diaphragm does not seem to be the cause, since the ability to breathe in does not drop during the pain (Morton and Callister, 2006), and it is not a cramp, since the electrical activity of the belly muscles does not rise (Morton and Callister, 2008).
How long before running should you avoid eating?
It is best to avoid big meals and large drinks in the 2 hours before exercise, and 3 to 4 hours if you are prone to side stitches (Morton and Callister, 2015). At a race in Sydney, having eaten a lot 1 to 2 hours before the start made side stitches more common, while the type of meal made no difference (Morton et al., 2005). A very sugary fruit juice drunk just before caused more side stitches than water (Morton et al., 2004).
Why is a side stitch more often on the right?
A side stitch is more often on the right, and no one knows exactly why: in Sydney, 46% of people affected had it on the right and 23% on the left (Morton et al., 2005). One idea is the position of the liver, under the right half of the diaphragm. Younger people feel it more often on the left (Morton and Callister, 2002).
Do side stitches get rarer with age and training?
Yes, side stitches become rarer and milder with age: 77% of people under 20 had one in the past year, compared with 40% of those over 40 (Morton and Callister, 2015). Training often also makes them less frequent, while sex and body build make no difference (Morton and Callister, 2002).
True or false?
A side stitch is a cramp of the diaphragm.
False. During a side stitch, the ability to breathe in does not drop (Morton and Callister, 2006) and the electrical activity of the belly muscles does not rise (Morton and Callister, 2008). The strongest lead is irritation of the peritoneum (Morton and Callister, 2015).
Swimmers get side stitches too.
True. In a survey of 965 athletes, 75% of swimmers had had one in the past year, about as many as runners (69%) (Morton and Callister, 2000).
A big meal before a run makes a side stitch more likely.
True. Having eaten a lot 1 to 2 hours before the start raised the risk at a race in Sydney (Morton et al., 2005). It is best to avoid big meals in the 2 hours before exercise (Morton and Callister, 2015).
This page as text
The same information as the charts, to read without animation: for each chart, the values at the main moments, then the notes with their level of evidence.
When does a side stitch strike?
It can come at any point in a run, more often and more strongly after a big meal or a large drink. The percentages are measured; the curves are estimated.
| Minutes of running, age or minutes after the pain starts | Pain, big meal 1 to 2 h before (dotted) | Pain, light meal more than 2 h before (dotted) | Stomach filling (big meal) (dotted) | What happens |
|---|---|---|---|---|
| Start | 0 | 0 | 85 | The start of the run |
| 10 min | 27 | 3 | 80 | of running |
| 20 min | 58 | 12 | 75 | of running |
| 30 min | 68 | 18 | 70 | of running |
| 40 min | 64 | 16 | 66 | of running |
| 50 min | 60 | 14 | 62 | of running |
| 60 min | 56 | 12 | 58 | of running |
Key points
- A full stomach makes pain more likely (The first 10 minutes, Shown in humans)
Among 848 participants in a 14 km race in Sydney, runners who had eaten a lot 1 to 2 hours before the start got side stitches more often. What the meal contained made no difference. Source: Morton, Richards and Callister, "Epidemiology of exercise-related transient abdominal pain at the Sydney City to Surf community run", J Sci Med Sport, 2005 - 27% of participants on race day (From 10 to 22 min of running, Shown in humans)
During this race, 27% of participants got a side stitch: 30% of runners and 16% of walkers. For 42% of them, the pain hurt their race. Source: Morton, Richards and Callister, "Epidemiology of exercise-related transient abdominal pain at the Sydney City to Surf community run", J Sci Med Sport, 2005 - A sharp or pulling pain (From 22 to 34 min of running, Shown in humans)
When mild, the pain feels like a cramp or a pulling; when strong, it becomes sharp, like a stab. It is well localized for 79% of athletes, most often on the side of the belly, below the ribs (78%). Source: Morton and Callister, "Characteristics and etiology of exercise-related transient abdominal pain", Med Sci Sports Exerc, 2000 - Sometimes up to the shoulder tip (From 34 to 46 min of running, Shown in humans)
14% of athletes surveyed also feel pain at the tip of the shoulder. Those who get side stitches have it more often. Source: Morton and Callister, "Characteristics and etiology of exercise-related transient abdominal pain", Med Sci Sports Exerc, 2000 - Sports that jolt or twist the torso (After 46 min of running, Shown in humans)
Over a year, 75% of swimmers, 69% of runners and 62% of horse riders had a side stitch, compared with 32% of cyclists: it mainly hits sports where the torso moves up and down, or twists. Source: Morton and Callister, "Characteristics and etiology of exercise-related transient abdominal pain", Med Sci Sports Exerc, 2000 - Estimated curves (Throughout the run, Hypothesis)
The percentages in the notes are measured. The shape and height of the curves are estimates: everyone has their own pace.
Do side stitches decrease with age?
Yes: 77% of athletes under 20 get one in a year, compared with 40% after age 40 (Morton and Callister, 2015). Both percentages are measured; the curve linking them is estimated.
| Minutes of running, age or minutes after the pain starts | Athletes who had one in the past year (%) (dotted) | What happens |
|---|---|---|
| 10 yrs | 80 | 10 years old |
| 20 yrs | 76 | 20 years old |
| 30 yrs | 58 | 30 years old |
| 40 yrs | 41 | 40 years old |
| 50 yrs | 36 | 50 years old |
| 60 yrs | 34 | 60 years old |
| 70 yrs | 31 | 70 years old |
Key points
- 77% under age 20 (Up to age 20, Shown in humans)
Among athletes under 20, 77% had a side stitch in the past year; after 40, it is 40%. Source: Morton and Callister, "Exercise-related transient abdominal pain (ETAP)", Sports Med, 2015 - Less frequent and milder with age (From age 20 to 32, Shown in humans)
In 965 athletes from six sports, side stitches became rarer and less painful with age. Younger people felt them more often on the left. Source: Morton and Callister, "Factors influencing exercise-related transient abdominal pain", Med Sci Sports Exerc, 2002 - 10.5 times more common running than cycling (From age 32 to 44, Shown in humans)
At the same age, side stitches were 10.5 times more common in running and 9 times more in horse riding than in cycling. Being a man or a woman, or body weight, made no difference. Source: Morton and Callister, "Factors influencing exercise-related transient abdominal pain", Med Sci Sports Exerc, 2002 - Training often helps (From age 44 to 56, Shown in humans)
Those who trained more often got side stitches less often; but when the pain came, it was just as strong. Source: Morton and Callister, "Factors influencing exercise-related transient abdominal pain", Med Sci Sports Exerc, 2002 - A rounded upper back makes it more likely (From age 56, Shown in humans)
In 159 young athletes, those with a rounded upper back were more prone to side stitches; body shape, slim or stocky, played no role. Source: Morton and Callister, "Influence of posture and body type on the experience of exercise-related transient abdominal pain", J Sci Med Sport, 2010 - Estimated curve (At any age, Hypothesis)
Only the percentages under 20 and over 40 are measured. No one knows yet why side stitches decrease with age.
How do you get rid of a side stitch?
Slow down, breathe deeply and press on the sore spot while bending forward: the pain usually passes quickly. The percentages are measured; the curves are estimated.
| Minutes of running, age or minutes after the pain starts | Pain if you keep the same pace (dotted) | Pain if you slow down and breathe deeply (dotted) | What happens |
|---|---|---|---|
| Pain | 60 | 60 | The start of the pain |
| +2 min | 68 | 28 | 2 min after the pain starts |
| +4 min | 70 | 9 | 4 min after the pain starts |
| +6 min | 70 | 2 | 6 min after the pain starts |
| +8 min | 68 | 0 | 8 min after the pain starts |
| +10 min | 66 | 0 | 10 min after the pain starts |
Key points
- It is not a cramp (The first 1.5 minutes, Shown in humans)
In 14 people measured in the middle of the pain, the electrical activity of the muscles at the site of the stitch did not rise: it is not a muscle cramp. Source: Morton and Callister, "EMG activity is not elevated during exercise-related transient abdominal pain", J Sci Med Sport, 2008 - Nor the diaphragm, it seems (From 1.5 to 3 min, Shown in humans)
In 14 people measured during the pain, the ability to breathe in did not drop: the diaphragm does not seem directly involved. Source: Morton and Callister, "Spirometry measurements during an episode of exercise-related transient abdominal pain", Int J Sports Physiol Perform, 2006 - The best lead: the peritoneum (From 3 to 4.5 min, Shown in humans)
The peritoneum lines the belly wall and its organs. The part attached to the wall is sensitive: rubbed or stretched by a full stomach and the jolts, it best explains the pain, even in the shoulder. Source: Morton and Callister, "Exercise-related transient abdominal pain (ETAP)", Sports Med, 2015 - What athletes do (From 4.5 to 6 min, Shown in humans)
To find relief, 40% of athletes breathe deeply, 31% press on the sore spot, 22% stretch and 18% bend forward. Source: Morton and Callister, "Exercise-related transient abdominal pain (ETAP)", Sports Med, 2015 - Bend forward while tightening your belly (From 6 to 7.5 min, Shown in humans)
In 7 runners, bending forward while tightening the abs, tightening a belt around the waist or breathing out through pursed lips eased the pain within seconds. Source: Plunkett and Hopkins, "Investigation of the side pain 'stitch' induced by running after fluid ingestion", Med Sci Sports Exerc, 1999 - Before exercise: eat less (From 7.5 to 9 min, Shown in humans)
It is best to avoid big meals and large drinks in the 2 hours before exercise, and 3 to 4 hours if you are prone to side stitches. Source: Morton and Callister, "Exercise-related transient abdominal pain (ETAP)", Sports Med, 2015 - No fruit juice right before (After 9 min, Shown in humans)
In 40 athletes prone to side stitches, a very sugary reconstituted orange juice caused more of them than water, a sports drink or nothing at all. Source: Morton, Aragón-Vargas and Callister, "Effect of ingested fluid composition on exercise-related transient abdominal pain", Int J Sport Nutr Exerc Metab, 2004 - Estimated curves (Throughout, Hypothesis)
The pain fades quickly once the cause is removed (Morton and Callister, 2015); the shape of the curves is an estimate.
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Metabolive. "Why do I get a side stitch when running?" Updated October 29, 2026. https://metabolive.com/en/effort-stress/side-stitch.
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